Local Anomalies, Local Equivariant Cohomology and the Variational Bicomplex

The locality conditions for the vanishing of local anomalies in field theory are shown to admit a geometrical interpretation in terms of local equivariant cohomology, thus providing a method to deal with the problem of locality in the geometrical approaches to the study of local anomalies based on the Atiyah-Singer index theorem. The local cohomology is shown to be related to the cohomology of jet bundles by means of the variational bicomplex theory. Using these results and the techniques for the computation of the cohomology of invariant variational bicomplexes in terms of relative Gel'fand-Fuks cohomology introduced in [6], we obtain necessary and sufficient conditions for the cancellation of local gravitational and mixed anomalies.Comment: 36 pages. The paper is divided in two part

Optimized local modes for lattice dynamical applications

We present a new scheme for the construction of highly localized lattice Wannier functions. The approach is based on a heuristic criterion for localization and takes the symmetry constraints into account from the start. We compare the local modes thus obtained with those generated by other schemes and find that they also provide a better description of the relevant vibrational subspace.Comment: 6 pages, ReVTeX, plus four postscript files for figure

Synchronization, Diversity, and Topology of Networks of Integrate and Fire Oscillators

We study synchronization dynamics of a population of pulse-coupled oscillators. In particular, we focus our attention in the interplay between networks topological disorder and its synchronization features. Firstly, we analyze synchronization time $T$ in random networks, and find a scaling law which relates $T$ to networks connectivity. Then, we carry on comparing synchronization time for several other topological configurations, characterized by a different degree of randomness. The analysis shows that regular lattices perform better than any other disordered network. The fact can be understood by considering the variability in the number of links between two adjacent neighbors. This phenomenon is equivalent to have a non-random topology with a distribution of interactions and it can be removed by an adequate local normalization of the couplings.Comment: 6 pages, 8 figures, LaTeX 209, uses RevTe

Thuisdealers, ritselaars en meesnoepers. Bewoners en bezoekers van grootstedelijke crackpanden

This article is based on ethnographical research in 24 crack houses in Amsterdam, Rotterdam and The Hague. Crack houses were defined as the homes of crack users where crack is being sold and smoked together with other users. All crack houses were located in disadvantaged, multi-ethnic neighbourhoods. Both residents and visitors were men and women, middle-aged, of various ethnic origin and with a long history of hard drug use. In addition to economic benefits for residents (crack sales, getting crack for free from visitors) and sometimes also for visitors, crack houses predominantly serve as a safe haven for drug use and as a social meeting place. Two types of crack houses were found: dealing houses (with ‘home sellers’) and home circuits (divided into ‘fixers’ who arrange or facilitate that crack is available, and ‘users-for-free’, who allow that crack is sold or delivered and used in their apartment, in exchange for a bit of crack). To reduce the risk of discovery and closure, residents take various measures, but less if they are not a legal resident of the apartment. In comparison with the Anglo-Saxon literature about crack houses, there is less ethnic segregation, a less aggressive atmosphere and less involvement with prostitution

From Feshbach-Resonance Managed Bose-Einstein Condensates to Anisotropic Universes: Some Applications of the Ermakov-Pinney equation with Time-Dependent Nonlinearity

In this work we revisit the topic of two-dimensional Bose-Einstein condensates under the influence of time-dependent magnetic confinement and time-dependent scattering length. A moment approach reduces the examination of moments of the wavefunction (in particular, of its width) to an Ermakov-Pinney (EP) ordinary differential equation (ODE). We use the well-known structure of the solutions of this nonlinear ODE to ``engineer'' trapping and interatomic interaction conditions that lead to condensates dispersing, breathing or even collapsing. The advantage of the approach is that it is fully tractable analytically, in excellent agreement with our numerical observations. As an aside, we also discuss how similar time-dependent EP equations may arise in the description of anisotropic scalar field cosmologies.Comment: 9 pages, 4 figure

Benchmark low-mass objects in Moving Groups

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.In order to compile a sample of ultracool dwarfs that will serve as benchmarks for testing theoretical formation and evolutionary models, we selected low-mass cool (>M7) objects that are potentially members of five known young Moving Groups in the solar neighbourhood. We have studied the kinematics of the sample, finding that 49 targets belong to the young disk area, from which 36 are kinematic member of one of the five moving groups under study. Some of the identified low-mass members have been spectroscopically characterised (T-eff, log g) and confirmed as young members through a detailed study of age indicators

Emergency remote teaching in process simulation using DWSIM: a case study from DIQ-UMAG, Chilean Patagonia / Enseñanza remota de emergencia en simulación de procesos con DWSIM: un caso estudio DIQ-UMAG, Patagonia Chilena

Due to the worldwide COVID-19 pandemic, Chilean universities were forced to transition from face-to-face classes to online instruction. In response, the Department of Chemical Engineering (DIQ) at the University of Magallanes sought alternative strategies for remote teaching. This article reports on their experience of delivering technical process simulation skills to their final-year undergraduate chemical engineering students. Due to difficulties connecting with the commercial software Aspen HYSYS, which was housed at the university, the department turned to the open-source software, DWSIM, as an alternative. The material content was adapted, and video tutorials were created to meet learning objectives. The software was taught in a new module within the Project Engineering course to develop the skills needed for students to design and simulate a chemical plant. Positive feedback and constructive criticism were received from the students through anonymous surveys and discussion forums. In response, DIQ launched its YouTube channel, DIQ_DWSIM, which has had a positive impact on Spanish-speaking individuals seeking to learn DWSIM. Additionally, two universities have used the channel as support material for their process simulation courses. A second survey of the YouTube audience has further solidified the value of this open online educational resource for higher education learning

Time series modeling of cell cycle exit identifies Brd4 dependent regulation of cerebellar neurogenesis

Cerebellar neuronal progenitors undergo a series of divisions before irreversibly exiting the cell cycle and differentiating into neurons. Dysfunction of this process underlies many neurological diseases including ataxia and the most common pediatric brain tumor, medulloblastoma. To better define the pathways controlling the most abundant neuronal cells in the mammalian cerebellum, cerebellar granule cell progenitors (GCPs), we performed RNA-sequencing of GCPs exiting the cell cycle. Time-series modeling of GCP cell cycle exit identified downregulation of activity of the epigenetic reader protein Brd4. Brd4 binding to the Gli1 locus is controlled by Casein Kinase 1δ (CK1 δ)-dependent phosphorylation during GCP proliferation, and decreases during GCP cell cycle exit. Importantly, conditional deletion of Brd4 in vivo in the developing cerebellum induces cerebellar morphological deficits and ataxia. These studies define an essential role for Brd4 in cerebellar granule cell neurogenesis and are critical for designing clinical trials utilizing Brd4 inhibitors in neurological indications

Matter-Wave Solitons in the Presence of Collisional Inhomogeneities: Perturbation theory and the impact of derivative terms

We study the dynamics of bright and dark matter-wave solitons in the presence of a spatially varying nonlinearity. When the spatial variation does not involve zero crossings, a transformation is used to bring the problem to a standard nonlinear Schrodinger form, but with two additional terms: an effective potential one and a non-potential term. We illustrate how to apply perturbation theory of dark and bright solitons to the transformed equations. We develop the general case, but primarily focus on the non-standard special case whereby the potential term vanishes, for an inverse square spatial dependence of the nonlinearity. In both cases of repulsive and attractive interactions, appropriate versions of the soliton perturbation theory are shown to accurately describe the soliton dynamics.Comment: 12 pages, 5 fugure